The invention describes a method for detecting biomolecules and, more particularly, to a method using an electrochemical sensor device for detecting biomolecules based on self-assembled nanoporous films on conducting electrodes.
Electrochemical methods are useful in the detection and analysis of biomolecules because they can be simple, fast, sensitive, reliable and inexpensive. These methods are particularly suitable for reduction-oxidation (redox) active proteins and enzymes. However, many biomolecules are not redox active and do not produce an electrochemically detectable signal. Therefore, most electrochemical assays require the target to be labeled with a redox active agent (markers or indicators) or an enzyme.
There has been an increasing interest in sensitive, labeling-free electrochemical detection for biomolecules. Enzyme catalyzed precipitation on an electrode has been investigated for detection for biomolecules. The diffusion of ferrocene markers in the bound layer for avidin-biotin coupling has also been studied. Other researchers have studied various redox complexes that were sensitive to their chemical environments for use in biochemical detection. Recently, functionalized conjugated conductive polymers as the electrodes have shown encouraging results. Impedance and capacitance measurement were also investigated for direct measurement.
Besides proteins, electrochemical methods are widely studied for deoxyribonucleic acid (DNA) analysis. Most methods are based hybridization with labeled target biomolecules. Recently, a reagentless method for sequence-specific DNA detection was developed. This method depends on the conformation change of a beacon molecule—a DNA molecule composed of a hairpin-like DNA-loop structure upon hybridization. Other labeling free analysis includes methods to measure a change in intrinsic redox properties, catalytic reactions with a redox mediator, formation of electroactive oxidized product on the electrode, and stripping of detectable subunits.